package ChatRoom;
import java.io.*;
import java.net.*;
import java.util.*;
public class ServerService {
 boolean stat = false;
 ServerSocket ss = null;
 
 List<Client> clients = new ArrayList<Client>();//用于存客户端
 
 public static void main(String[] args) {
  new ServerService().start();
 }
 
 public void start(){
  try {
   ss = new ServerSocket(8888);
   stat = true;
  } catch(BindException e){  //Sever端已经运行，当重复运行时抛异常
   System.out.println("端口正在使用中。。。。");
   System.out.println("请关掉相关程序并重新运行服务器！"); //还会抛别的异常，所以直接关闭窗口
   System.exit(0);
  } catch(IOException e) {
   e.printStackTrace();
  }
  
  try{
   while(stat){
    Socket s = ss.accept();
System.out.println("a client connected!" );  //测试语句写在最左边，以后没用可以删除或注掉
    Client c = new Client(s);    //每建立一个客户端，就new一个客户端对象，启动一个线程
    new Thread(c).start();
    clients.add(c);  //勿忘写，将每个客户端加入到容器里
   }
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   try {
    ss.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
 }

 class Client implements Runnable {
  private Socket s;
  private DataInputStream dis;
  private DataOutputStream dos;
  private boolean cont = false;
  
  public Client(Socket s){
   this.s = s;  
   try {
    dis = new DataInputStream(s.getInputStream());//初始化
    dos = new DataOutputStream(s.getOutputStream());
    cont = true;
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  
  public void send(String str){  //用于发送给客户端
   try {
    dos.writeUTF(str);
   } catch (IOException e) {
    clients.remove(this);  //移除那个退出的对象
    System.out.println("一个客户退出了");
    //e.printStackTrace();
   }
  }
  
  public void run() {
   try{
    while(cont){
     String str = dis.readUTF(); //阻塞式方法
System.out.println(str);
     for(int i=0; i<clients.size(); i++){
      Client c = clients.get(i);  //取客户端
      c.send(str);  
     }
     /*     另外两种方法，但不适用，它会锁定服务端
     for(Iterator<Client> it = clients.iterator(); it.hasNext();){
      Client c = it.next();
      c.send(str);
     }
     
     Iterator<Client> it = clients.iterator();
     while(it.hasNext()){
      Client c = it.next();
      c.send(str);
     }
     */
    }
   } catch (EOFException e){   //readUTF()阻塞式方法，所以关闭客户端会抛异常
    System.out.println("Client closed!");
   } catch (IOException e) {
    e.printStackTrace();
   } finally {
    try {
     if(dis != null) dis.close();
     if(dos != null) dos.close();
     if(s != null) {
      s.close();
      s = null;//更严格的方法，等于空就没人去用了，垃圾收集器就回收走
     }
    } catch (IOException e) {
     e.printStackTrace();
    } 
   }
  }
 }
}
